It is known that changes of the aerodynamic performance or properties of the rotor blades of a wind turbine may both impact the performance of the rotor hub and change the optimal control rule usually embracing a number of control settings, operational parameters, etc., and may consequently lead to a decrease of the power production of the wind turbine. Thus, a wind turbine will operate suboptimal and a specific rated power production may not be reached in this case.
The aerodynamic performance of the rotor blades is mainly negatively influenced due to specific climatic conditions such as temperature, humidity etc. which may lead to the formation of ice at least partially covering the surface of the rotor blades. This problem usually occurs during winter.
Thereby, it is a problem that rotor blades being at least partially covered with ice usually tend to stall due to the weight and shape of the ice and/or because the currently control rule typically assuming blades free of ice is no longer appropriate or suitable, which usually leads to a significant decrease of the power output of the wind turbine. Further, icy or frosted rotor blades may also encounter high mechanical loads as well as thrust.
Usually, operation and/or control rules or strategies of modern wind turbines are based on the adjustment of proper pitch-angle references, power output references and/or torque references, etc. which adjustment relates to a known aerodynamic performance of the rotor blades which is essentially defined by their shape, dimensions, etc. Thereby, usually respective power values defining a certain amount of power which the generator has to submit to at least one electrical converter unit of the wind turbine are dynamically set by or included in a respective control rule.
However, in the case of the rotor blades being at least partially covered with ice and hence differ in their aerodynamic performance, proper operation and/or control rules or strategies of wind turbines are usually not available.